Electric transfer-switch



(No Model.)

A.EKSTR5M.

ELECTRIC TRANSFER- swmm.

No. 538,670. Patented May 7, 1895.

3 H 0 t i 0 O- Q m 0 O Y, a o o 4 E V M NEEEEE. INJENTm fllrmw M 6%UNITED STATES PATENT OFFICE.

AXEL EKSTROM, OF LYNN, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OFBOSTON, MASSACHUSETTS.

ELECTRIC TRANSFER-SWITCH.

SPECIFICATION forming part of Letters Patent No. 538,670, dated May '7,1895.

Application filed September 7, 1893. Serial No. 84,962. (No model.)

$0 6055 whom it may concern.-

Be it known that I, AXEL EKSTROM, a citizen of the United States,residing at Lynn, in the county of Essex and State of Massachusetts,have invented a certain new and useful Improvement in ElectricTransfer-Switches, of which the following is a specification.

My invention relates to electric switches, and consists in animprovement in devices of the kind known as transfer-switches, that is,switches by means of which a circuit containing translating devices canbe connected to any of a plurality of generators or sets of generatorsat a power station or source of supply. The switch which has been mostcommonly used forthis purpose is that known as the jack knife switch,which is so well known as to require no further definition.

My invention consists in an improvement over this form of switch andembodies details of construction whereby the switch is more readilyoperated and the danger of injury to the apparatus orthe operator byarcing at the contacts is obviated.

In carrying out my invention I provide a thick plate or base ofrefractile, non-pliable, insulating material, such as slate, on one sideof which are arranged the terminals or contacts of the switch, as willbe hereinafter more fully described, and on the other side the operatinghandle which turns a shaft carrying the movable contacts, said shaftpassing through said base and turning in a suitable bearing providedtherefor. In this manner the operators hand is absolutely protectedagainst injury by arcing at the contacts, and the handle may be soarranged that a simpler and easier movement suffices for the operationof the switch than in the jack knife switch above mentioned.

In the accompanying drawings, Figure 1 is a plan view of the switch,showing the circuit connections; and Fig. 2 is a side elevation of thesame.

Referring to Fig. 1 the terminals A and A are permanently connectedrespectively to the positive and negative wires of a circuit, 1, 2,containing translating devices 3. These terminals consist of plates inplanes parallel to that of the base-plate D, and are held in position bysupports E riveted or otherwise fastened in said base-plate. Thecontactplates forming these terminals are not in the same plane, theterminal A being further removed from thebase-plate D than the t-erminalA. The object of this arrangement will be hereinafter more fullydescribed. Corresponding to these terminals are two other sets ofterminals B and B and O and C permanently connected respectively to thepositive and negative bus-bars of generators, sets of generators orother current sources, X and Y. Of these last named terminals B and Oare in the same plane as A, as best shown in Fig. 2. In other words allthe positive terminals are in one plane and all the negative terminalsin another. The switch proper, whereby electrical connection is effectedbetween the said terminals, comprises two bars F, and F, having riveted,screwed, or otherwise fastened at their ends brushes or similar contactdevices f, adapted to connect with the said terminals. In the positionshown in the drawings, one of the said bars F connects terminal A toterminal B and the other connects terminal A to terminal B. Thecurrent-source X is thus connected to the circuit 1, 2, while thecurrentsource Y is open-circuited, as will be readily seen by referenceto Fig. 1 without further description. The said bars F F are fastened toopposite sides of a plate f, preferably bent a little to one side of themiddle, as shown in Fig. 2, so as to separate the said bars by a spacesomewhat greater than the thickness of the plate. One ofsaid bars isthus brought into the plane of and adapted to connect with the terminalsA, B, C, while the other is in theplane of terminals A, B, O. The saidplatef is carried by a shaft f and has a bearing in a bushing f whichpasses through the base D and is secured by a nut or screw-cap J. A.handlef which may be of any suitable shape, preferably bent as bestshown in Fig. 2 is attached to said shaft on the outer side of the baseD for the operation of the switch. If now the handle be moved from theposition shown in Fig. 1 through an arc of one hundred and twentydegrees, the bars F and F; with their brushesf will be transferred fromthe terminals B and B to the terminals 0 and O, at the same timechanging their position with relation to the terminals A and A so thatthe end ,of the bar F which is shown as engaging with terminal B willpass around until it engages with A, while the end shown as engagingwith A will pass around until it touches C. Thus the terminal A isconnected to 0 instead .of to B, and in the same manner the'bar Fconnects A and 0 instead of A and B. When the switch is in this positionthe current source Y is connected to the circuit 1, 2, while the sourceX is out of circuit. It will be seen that in effecting this change thebar F which is in the same plane with terminals A, B.

and 0 passes under terminal 13 at one end and terminal 0 at the other,while in the same way the bar F passes over terminals B and O. In orderto prevent the possible springing across of an arc between these contactpoints thus brought into proximity, I provide thin plates or septa GandG of insulating material below the bar F and above the bar Frespectively. These plates or septa are also fastened to the plate f, bymeans of screws f, and said screws may also serve to fasten the bars Fand Fas shown. The septa, therefore, move with the said bars, and assaid bars pass the terminals with which they are not adapted to'engage,the septa come between said bars and said terminals, thus preventing theformation of an arc. In order that the switch may be positive in itsaction, I provide on the shaftf" acamf against the surface of whichbears a roller or slidef As the handle f is operated, the said campushes against said roller which is acted upon by a spring f. The cam isso shaped that when the switch is half way between its oper ativepositions the apex of said cam is acted on by the spring, so that whenthe central position is passed in either direction the said spring tendsto actuate the switch until the operative position is reached. The saidspring may conveniently be seated, as shown in a recess or pocket f inthe casting which forms the bushing but this is obviously not essential.Lugs f at the ends of the cam limit the movement of the switch andprevent it from going beyond the terminals with which it is desired tomake contact.

In the drawings, Fig. 1, plug switches H are shown on the generatorcircuit X and Y, which may be used, if desired, in connection with thetransfer switch which forms the subject of my invention. The brushes, or'contact-devices f are shown as made up of layers of thin plates orlaminze which may be of copper or any good conducting material rivetedor screwed, as described, to the arms or bars F and F and embracing theterminals A, A, &c., as good electrical contact capable of taking careof large currents is thus effectively secured. It is not, however,essential that these brushes should be made in this way, as any goodelectrical contact device may be employed. Other modifications moreover,

might be made in the arrangement of the apparatus,'and I do nottherefore intend to limit myself to the exact construction shown in thedrawings, but only to the essential features thereof as set forth in thefollowing claims.

Having thus described my invention, what I claim as new, and wish toprotect by Letters Patent of the United States, is

1. In an electric switch, the combination with a set of terminalsconnected respectively with the positive wires of a work circuit and twoor more sources of current, of a corresponding set of terminalsconnected to the negative wires of said work-circuit and said sources ofcurrent, all of said positive terminals being in the same plane and allof said negative terminals being in another plane parallel thereto, aswitch-arm or connector in the plane of said positive terminals adaptedto vary the connections therebetween, a second switch-arm in the planeof said negative terminals adapted to correspondingly vary theconnections therebetween, and an operating device for simultaneouslymoving both of said switch arms and thus connecting said work circuit toany of said sources of current,

as set forth.

2. An electric switch comprising a set of positive terminals arranged onthe circumference of a circle, a set of negative terminals similarlyarranged on the circumference of a circle concentric with the first, allof said positive terminals being in the same plane and all of saidnegative terminals being in another plane parallel thereto, a shaftturning in the common center of said circles and carrying switch arms orconnectors so situated as to form chords to the circumferences of saidcircles respectivelyand of such length as to bridge any twoadjacent'terminais situated on said circumferences, and an operatinghandle adapted to move said shaft through an arc predetermined by thesituation of said terminals, as set forth.

3. In an electric switch having sets of positive and negative terminalsmounted in different planes upon one side of the insulating base plate,substantially as described, the combination with switch-arms orconnectors adapted to bridge certain of said terminals, of insulatingsepta movable with said switcharms, a shaft passing through the baseplate and carrying said switch-arms and septa, a cam mounted on saidshaft, a spring acting on said cam, lugs at the end of said cam wherebysaid shaft is permitted to come to rest only at certain predeterminedpositions, and an operating handle for said shaft upon the other sideofsuch base plate from that upon which the switching apparatus is located,as set forth.

In witness whereofI have hereunto set my hand this 5th day of September,1893.

AXEL EKSTROM. Witnesses:

J OHN W. GIBBONEY, BENJAMIN B. HULL.

